Infusion container with multiple chambers and production method thereof

ABSTRACT

The present invention has an object to provide an infusion container with multiple chambers, where the peel strength of the boundary portion between one and another of multiple medicament chambers is stabilized irrespective of the construction material and structure of the film. The present invention provides an infusion container  10  with multiple chambers, which is formed from a thermoplastic resin film and has a plurality of medicament chambers  11  and  12  for housing medicaments, wherein the medicaments chambers  11  and  12  are liquid-tightly sealed by a peelable weak seal part  15 , the weak seal part  15  is formed to have a plurality of melt-bonding parts different in the melt-bonding strength, the strong melt-bonding part having a largest melt-bonding strength among these melt-bonding parts is dispersed and distributed in the weak seal part  15 , and the total occupied area of the strong melt-bonding part is less than 25% of the area of the weak seal part  15.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/412,796, filed on Sep. 24, 2002, which is hereby incorporated byreference, and is based on Japanese Patent Application No. 2002-093177filed on Mar. 28, 2002 and Japanese Patent Application No. 2003-023436filed on Jan. 31, 2003, which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an infusion container with multiplechambers, where a plurality of medicaments can be separately housed andthese medicaments can be easily mixed on use, and also relates to aproduction method thereof.

BACKGROUND ART

As a practical treatment, a plurality of medicaments are mixed andadministered to a patient, for example, a vitamin compound or the likeis mixed in physiological saline and the solution is injected orinstilled to a patient. In the case of mixing a plurality of medicamentsas such, if these are previously mixed, degeneration may occur dependingon the kind of the medicament. Therefore, an infusion container withmultiple chambers is being used, where a plurality of medicaments havingpossibility of degeneration can be separately housed and can be mixedimmediately before use. In some infusion containers with multiplechambers, the body is formed of a thermoplastic resin film such aspolyolefin.

Such an infusion container with multiple chambers, which is formed of athermoplastic resin film, is necessary to satisfy the requirement thatthe boundary portion between medicament chambers is liquid-tightlysealed in the stage before mixing a plurality of medicaments but onmixing the plurality of medicaments, the boundary portion can be easilypeeled apart to open the path between chambers and the medicaments canbe rapidly mixed. Therefore, a large number of studies have been made onthe method for forming the boundary portion.

For example, JP-A-2-4671 (the term “JP-A” as used herein means an“unexamined published Japanese patent application”) and JP-A-2000-14746disclose a technique of forming the portion participating in theadhesion from a specific material so as to form a readily peelableboundary portion. Furthermore, JP-A-11-169432 describes a method ofcoating an easily peelable coating agent on the inner surface of theboundary portion and thereby facilitating the peeling.

On the other hand, JP-A-8-24314 discloses a technique where two barseach with a seal edge having a specific shape are used in combination asa heat seal bar for use at the sealing of the boundary portion and thefilm is sandwiched therebetween while precisely controlling thepositions of these seal edges, so that the boundary portion can have anappropriate peel strength.

However, the techniques disclosed in JP-A-2-4671 and JP-A-2000-14746have a problem that since an easily peelable boundary portion is formed,the portion must be composed of multiple layers but a single layer filmcannot be applied and the production of film costs highly. Also, thetechnique described in JP-A-11-169432 has a problem that a specificcoating agent is necessary and the production step or production costincreases.

In the method disclosed in JP-A-8-24314, it is not essential to form afilm having a multilayer structure or use a coating agent, but sealedges of heat seal bars for sealing the boundary portion must be alignedand if these positions are misaligned, the peel strength of the formedboundary portion is greatly dispersed among infusion containers eachhaving multiple chambers. Furthermore, in the case where the heat sealbar has a narrow perforation pitch, the positions are very difficult toalign and even if the heat seal temperature is maintained at a fixedtemperature, the peel strength may be dispersed among infusioncontainers each having multiple chambers. It has been demanded to stablyproduce an infusion container with multiple chambers, having a desiredpeel strength.

DISCLOSURE OF INVENTION

The present invention has been made under these circumstances and anobject of the present invention is to provide an infusion container withmultiple chambers, where the peel strength of the boundary portionbetween one and another of multiple medicament chambers is stabilizedirrespective of the construction material and structure of the film.Another object of the present invention is to provide a method capableof easily producing such an infusion container having multiple chamberswith good productivity.

The present inventors have found that when the weak seal part forpartitioning multiple medicament chambers from each other is formed tohave a plurality of melt-bonding parts different in the melt-bondingdegree and the total occupied area of the strong melt-bonding parthaving a largest melt-bonding strength among these melt-bonding parts iscontrolled, the above-described objects can be attained. The presentinvention has been accomplished based on this finding. The term “largemelt-bonding strength” as used herein means that the power necessary forpeeling apart the portion which is melt-bonded and sealed is large.

In addition, the term “melt-bonding” as used in the present inventionmeans adhering by pressing while heating, and not only indicates thecondition that thermoplastic resin films are melted and are completelyunited therewith, so that the boundary thereof is unclear, but alsoincludes the condition that the boundary between the thermoplastic resinfilms is observed, so long as a liquid-tight seal is maintained.

The infusion container with multiple chambers of the present inventionis formed from a thermoplastic resin film and has multiple medicamentchambers for housing medicaments, wherein at least a part of theperipheral edge of the infusion container with multiple chambers isliquid-tightly sealed by a strong seal part, respective medicamentchambers are liquid-tightly sealed by a peelable weak seal part, theweak seal part is formed to have a plurality of melt-bonding partsdifferent in the melt-bonding strength, the strong melt-bonding parthaving a largest melt-bonding strength among these melt-bonding parts isdispersed and distributed in the weak seal part and the total occupiedarea of the strong melt-bonding part is less than 25% of the area of theweak seal part.

The method for producing an infusion container with multiple chambers ofthe present invention is a method for producing an infusion containerwith multiple chambers, which has multiple medicament chambers forhousing medicaments and in which respective medicament chambers areliquid-tightly sealed by a peelable weak seal part, the methodcomprising a weak seal step of sandwiching two superposed thermoplasticresin films from both sides using two heat seal bars to form a weak sealpart having a plurality of melt-bonding parts different in themelt-bonding strength, wherein the weak seal step is performed such thatthe total occupied area of the strong melt-bonding part having a largestmelt-bonding strength among those melt-bonding parts and being dispersedand distributed in the weak seal part is less than 25% of the area ofthe weak seal part.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing one example of the infusion container withmultiple chambers of the present invention.

FIG. 2 is a partially enlarged plan view showing the weak seal part ofthe infusion container with multiple chambers of FIG. 1.

FIG. 3 is a further partially enlarged plan view showing the weak sealpart of the infusion container with multiple chambers of FIG. 1.

FIG. 4 is a perspective view of the heat seal bar used for forming theweak seal part of the infusion container with multiple chambers of FIG.1.

FIG. 5 is a cross-sectional view along V-V′ in FIG. 4.

FIG. 6(a) is a cross-sectional view along I-I′ in FIG. 3 and FIG. 6(b)is a cross-sectional view along II-II′.

FIG. 7 is a partially enlarged plan view showing the weak seal part ofthe infusion container with multiple chambers according to anotherexample of the present invention.

FIG. 8 is the same plan view as FIG. 7.

FIG. 9 is a perspective view of the heat seal bar used for forming theweak seal part of the infusion container with multiple chambers of FIG.7.

FIG. 10 is a cross-sectional view along III-III′ in FIG. 8.

FIG. 11 is a partially enlarged plan view showing the weak seal part ofthe infusion container with multiple chambers according to anotherexample of the present invention.

FIG. 12 is a cross-sectional view along IV-IV′ in FIG. 11.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention is described in detail below.

[First Embodiment]

FIG. 1 is one example of the infusion container with multiple chambersof the present invention, which is formed from a thermoplastic resinfilm and has two medicament chambers 11 and 12 where a medicament willbe filled. In the infusion container 10 with multiple chambers of thisexample, one medicament chamber 11 is connected by a medicament chargingpart 13 and another medicament chamber is connected by a medicamentinlet/outlet part 14 for charging a medicament thereinto and onadministering the medicament to a patient, discharging the medicamentfrom the chamber.

In this infusion container 10 with multiple chambers, those twomedicament chambers 11 and 12 are separated by a liquid-tight weak sealpart 15. After medicaments are filled in respective medicament chambers11 and 12, the weak seal part 15 is heat-sealed such that the portioncan be peeled apart by externally applying a force to at least eitherone of the medicament chambers 11 and 12 and the medicaments can berapidly and easily mixed with each other on demand.

On the other hand, the peripheral edge of this infusion container 10with multiple chambers is liquid-tightly closed by a strong seal part 16which is not peeled apart even when a force is externally applied to themedicament chamber 11 or 12. In this part, the thermoplastic resin filmsare heat-sealed and strongly melt-bonded. In this example, the strongseal part 16 is formed throughout the peripheral edge of the infusioncontainer 10 with multiple chambers, however, for example, in the caseof using a cylindrical thermoplastic resin film as the material, thestrong seal part 16 may be formed only on both edges in the longitudinaldirection of film (in the Figure, upper and lower end parts). The strongseal part 16 is not always necessary to be formed on the entireperipheral edge.

The weak seal part 15 of the infusion container 10 with multiplechambers of this example is formed by sandwiching two superposedthermoplastic resin films from both surface sides by two heat seal barseach having a specific seal edge formed on the seal surface, which isdescribed in detail later. As partially shown in the enlarged plan viewof FIG. 2, this part is formed to have three melt-bonding partsdifferent in the melt-bonding strength, namely, a strong melt-bondingpart 15 a, a medium melt-bonding part 15 b and a weak melt-bonding part15 c.

The strong melt-bonding part 15 a having a highest melt-bonding strengthamong these melt-bonding parts has a nearly square form and almostuniformly dispersed and distributed in the weak seal part 15. The weakmelt-bonding part 15 c having a lowest melt-bonding strength in the weakseal part 15 has a nearly square form larger than the strongmelt-bonding part 15 a and is almost uniformly dispersed and distributedin the weak seal part 15. The medium melt-bonding part 15 b having amelt-bonding strength between the strong melt-bonding part 15 a and theweak melt-bonding part 15 c has a nearly rectangular form and similarly,almost uniformly dispersed and distributed in the weak seal part 15.Among the strong melt-bonding part 15 a, the medium melt-bonding part 15b and the weak melt-bonding part 15 c, the thickness of the strongmelt-bonding part 15 a is smallest and the thickness of the weakmelt-bonding part 15 c is largest.

Furthermore, the strong melt-bonding part 15 a having a highestmelt-bonding strength among these three kinds of melt-bonding parts isformed such that the total occupied area thereof is less than 25% of theentire area of the weak seal part 15.

Therefore, the peel strength of the weak seal part 15 is appropriatelycontrolled and the power necessary for opening the part, namely, theopening strength also becomes appropriate, so that the weak seal partthus formed can maintain the liquid-tight separation between themedicament chambers 11 and 12 at an ordinary time but when a force isexternally applied to the medicament chamber 11 or 12, can be easilypeeled apart and opened.

If the total of occupied areas of respective strong melt-bonding parts15 a in the weak seal part 15 is 25% or more, the opening strength isexcessively large and the weak seal part 15 cannot be easily peeledapart on demand, whereas if it is less than 0.01%, the opening strengthis small and the weak seal part may be peeled apart by an impact or thelike. Accordingly, the total of occupied areas of respective strongmelt-bonding parts 15 a is preferably from 0.01 to 25%, more preferablyfrom 0.01 to 15%, still more preferably from 0.05 to 10%.

In the infusion container 10 with multiple chambers of this example,respective strong melt-bonding parts 15 a are distributed such that theaverage of spaces between respective adjacent strong melt-bonding parts15 a, namely, the average space A, and the average of distances betweenrespective adjacent strong melt-bonding parts 15 a, namely, the averagedistance B, satisfy the following formula (1):B<2A  (1)

Here, the distance between adjacent strong melt-bonding parts 15 a is,as shown by the symbol B₁ in FIG. 3, a distance between centroids ofadjacent strong melt-bonding parts 15 a and the average distance B is anaverage of these distances. Also, the space between adjacent strongmelt-bonding parts 15 a is, as shown by the symbol A₁, a distance fromthe distal end of one strong melt-bonding part 15 a to the distal end ofanother strong melt-bonding part 15 a on a line connecting centroids ofadjacent strong melt-bonding parts 15 a and the average space A is anaverage of these distances.

When the strong melt-bonding part 15 a is distributed to satisfy formula(1), the opening strength of the weak seal part 15 can be moreunfailingly and easily controlled. Furthermore, when the averagedistance B is 1 mm or more, preferably 1.5 mm or more, more preferably 2mm or more, the opening strength of the weak seal part 15 can be moreunfailingly and easily controlled. The upper limit of the averagedistance B is preferably 10 mm, more preferably 5 mm. If B>2A, theopening strength becomes too large and even when a force is applied tothe medicament chamber 11 or 12 on demand, the weak seal part 15 may notbe easily opened.

In this example, each strong melt-bonding part 15 has a nearly squareplane having one side length of almost 0.2 mm (area: 0.04 mm²), theaverage space A is 1.8 mm, the average distance B is 2 mm and the totaloccupied area of the strong melt-bonding part is 1%. In the case whereeach strong melt-bonding part 15 a has such a plane, each area ispreferably 1 mm² or less, more preferably 0.5 mm² or less.

According to this infusion container 10 with multiple chambers, thetotal of occupied areas of respective strong melt-bonding parts 15 a inthe weak seal part 15 is less than 25%, so that the peal strength of theweak seal part 15 can be appropriately controlled to give a properopening strength and even when the thermoplastic resin film used is asingle layer film of, for example, polyolefin resin having crystallinityand the peel strength thereof is relatively difficult to control, thepeel strength of the formed weak seal part 15 can be controlled, as aresult, the opening strength can be easily controlled to fall in anappropriate range without fail. The method for measuring the openingstrength is described later in Examples.

In the case of heat-sealing a polyolefin resin film havingcrystallinity, the sealing is usually performed at a temperature nearthe melting point of this resin. However, in the vicinity of the meltingpoint, melting of the crystal abruptly proceeds and even by a slightchange in the heat seal temperature, the peel strength of the formedweak seal part 15 may fluctuate. If the peel strength fluctuates assuch, the opening strength of the weak seal part 15 may be dispersedamong individual infusion containers 10 each having multiple chambersand an infusion container with multiple chambers may not be produced tohave a stable performance. However, when the area of the strongmelt-bonding part 15 a is controlled as above, even if the thermoplasticresin film used is a single layer film having crystallinity and issealed at a temperature near the melting point thereof and also the heatsealing temperature is slightly changed, the dispersion in the peelstrength of the weak seal part 15 can be suppressed to the minimum andan infusion container 10 with multiple chambers having a fixed openingstrength can be stably produced.

The thermoplastic resin film for use in the infusion container 10 withmultiple chambers of this example is preferably a polyolefin resinbecause this is inexpensive and excellent in the transparency andflexibility. Examples thereof include polyethylene-base resins such ashigh-density polyethylene, medium-density polyethylene, high-pressurelow-density polyethylene, low-density polyethylene, linear low-densitypolyethylene and ethylene-vinyl acetate copolymer; olefin-baseelastomers such as ethylene-butadiene random copolymer;polypropylene-base resins such as polypropylene, ethylene-propylenerandom copolymer and α-olefin-propylene random copolymer; and a mixturethereof. According to this infusion container 10 with multiple chambers,a specific resin needs not be selected and used for forming the weakseal part 15 as described above and therefore, a resin usable as thethermoplastic resin film in the medical field can be used without anyparticular limitation. Also, a film comprising a vinyl chloride, anethylene-vinyl acetate copolymer, a polyether sulfone, a cyclicpolyolefin, a cyclic polyolefin copolymer, a styrene-base elastomer suchas hydrogenated styrene ethylene butadiene copolymer, a mixture of twoor more of these resins, or a mixture of such a resin with theabove-described polyolefin-base resin can be used. These resins may bepartially crosslinked for the purpose of elevating heat resistance orthe like.

The thermoplastic resin film used may be a single layer film composed ofone kind of film or a multilayer film obtained by laminating multiplekinds of films. In the case of a single layer film, a film comprising alinear low-density polyethylene, an ethylene propylene random copolymer,an ethylene propylene block copolymer, or a mixture of apolypropylene-base resin and a styrene-base elastomer is preferredbecause of excellent transparency and flexibility. In the case of amultilayer film, examples thereof include films comprising, from theouter side of the infusion container with multiple chambers,high-density polyethylene/linear low-density polyethylene,medium-density polyethylene/ low-density polyethylene/high-densitypolyethylene, or high-density polyethylene/low-densitypolyethylene/high-density polyethylene.

In the multilayer film, the inner layer may be composed of a resincomposition which enables easy peeling.

The method for producing the film is not particularly limited andexamples thereof include production methods using T-die casting,water-cooling inflation molding, blow molding or lamination molding. Inview of transparency, T-die casting and water-cooling inflation moldingare preferred.

The thermoplastic resin film used has a thickness of 5 to 1,000 μm,preferably on the order of 50 to 500 μm.

The weak seal part 15 of the infusion container 10 with multiplechambers can be formed by sandwiching superposed two thermoplastic resinfilms from both surface sides using two heat seal bars 20 and 21 havingseal edges 20 a and 21 a, respectively, on the seal surface as shown inFIG. 4. As for the superposed two thermoplastic resin films, two sheetsin the film form may be superposed or a film previously molded into acylindrical form may be used. In addition to these two thermoplasticresin films, a new film may be inserted and sealed in the weak seal part15.

In the two heat seal bars 20 and 21 of FIG. 4, as seen in the enlargedview of FIG. 5, a plurality of projected streaks with a width W of 0.2mm are formed as the seal edge 20 a or 21 a on the seal surface to runin parallel with each other at a distance P of 2 mm. These two heat sealbars 20 and 21 are disposed such that the projected streak seal edge 20a of one heat seal bar 20 and the projected streak seal edge 21 a ofanother heat seal bar 21 are crossed at 90°, thereby sandwichingsuperposed two thermoplastic resin films.

As a result, the portion contacted and pressed from both surfaces of thethermoplastic resin film by seal edges 20 a and 21 a, respectively,becomes a strong melt-bonding part 15 a having a small thickness andbeing strongly melt-bonded, and the portion not contacted from bothsurface sides by either the seal edge 20 a or 21 a of the heat seal bars20 and 21 is heated indirectly by heat conduction or the like andbecomes a weak melt-bonding part 15 c which is weakly melt-bonded. Theportion contacted only by the seal edge 20 a or 21 a of one heat sealbar 20 or 21 becomes a medium melt-bonding part 15 b having amelt-bonding strength between the strong melt-bonding part 15 a and theweak melt-bonding part 15 c.

Accordingly, by using heat seal bars 20 and 21 where the width W, thedistance P and depending on the case, the edge angle (which is describedlater) of seal edges are appropriately adjusted in advance such that thetotal area of the portions contacted and pressed from both surface sidesof the thermoplastic resin film by seal edges 20 a and 21 a,respectively, is less than 25% of the entire weak seal part 15, a weakseal part 15 having a fixed opening strength can be easily formed.

Furthermore, according to such a method, even if the heat sealtemperature is changed by about 1° C. from the optimal temperature, theopening strength of the obtained weak seal part 15 fluctuates only inthe range of 1,000 N or less, preferably 750 N or less. Namely, theelevation rate of opening strength is 1,000 N/° C., preferably 750 N/°C. In practice, the opening strength is preferably on the order of 300to 2,000 N, more preferably 300 to 1,500 N, and according to the methoddescribed above, even if the heat seal temperature slightly deviates,the opening strength readily falls in this range. The heat sealtemperature may be appropriately determined according to thethermoplastic resin film used. The seal edge 20 a or 21 a whichcomprises a plurality of projected streaks formed to run nearly inparallel, preferably has a width W of 1 mm or less, more preferably 0.5mm or less, and a distance P of 1 mm or more.

According to such a method, a weak seal part 15 having a desired openingstrength can be formed only by using heat seal bars 20 and 21 where thewidth W, the distance P and depending on the case, the edge angle of theseal edge 20 a or 21 a are adjusted such that the total occupied area ofthe strong melt-bonding part 15 a formed is less than 25% of the area ofthe weak seal part 15. Therefore, a strong seal step of liquid-tightlysealing the peripheral edge of the infusion container 10 with multiplechambers can be performed simultaneously with the weak seal step offorming the weak seal part 15 as such.

More specifically, heat seal bars (not shown) in the form capable ofsimultaneously sandwiching the peripheral edge of an infusion container10 with multiple chambers, where the strong seal part 16 is formed, andthe center part of the infusion container 10 with multiple chambers,where the weak seal part 15 is formed, are used, the seal edges 20 a and21 a in the portion of forming the weak seal part 15 are adjusted, asdescribed above, such that the total occupied area of the strongmelt-bonding part 15 a is less than 25%, and the seal edges in theportion of forming the strong seal part 16 are adjusted not to causepeeling of the seal part even when a force is applied to the medicamentchamber 11 or 12, whereby the weak seal part 15 and the strong seal part16 can be simultaneously formed only by one operation of sandwiching thethermoplastic resin films with heat seal bars.

As shown in FIG. 5, the edge angle α of the seal edge formed on the heatseal bar for forming the weak seal part 15 is preferably 120° or less.If the edge angle exceeds 120°, the area of the strong melt-bonding part15 cannot be easily controlled. The edge angle is preferably 90° orless, more preferably 60° or less.

As seen in FIGS. 6(a) and (b) which schematically show thecross-sectional views cut along the I-I′ line and the II-II′ line ofFIG. 3, respectively, the thus-formed weak seal part 15 a of theinfusion container 10 with multiple chambers is in the state that arecessed part is formed resulting from the seal edge 20 a or 21 a of theheat seal bar 20 or 21 coming into contact with the thermoplastic resinfilm. In the case of this example, recessed streaks 22 a having a widthof about 0.2 mm or slightly larger than that and running in parallel ata distance of about 2 mm from each other are formed on both surfaces ofthe weak seal part 15 following the shape of the seal edge contacted.Among these recessed streaks 22 a, some are the strong melt-bonding part15 a formed resulting from the seal edges 20 a and 21 a contact-pressingthe thermoplastic resin film from both surface sides, and the remainingportions are the medium melt-bonding part 15 b where the seal edge 20 aor 21 a comes into contact with the thermoplastic resin film only fromone side.

The thus-formed recessed streak 22 a is determined in correspondencewith the width W or distance P of the seal edges 20 a and 21 a, however,the width W′ shown is preferably about 1 mm or less and the distance P′is preferably about 1 mm or more. The width W′ is liable to be the sameas or slightly larger than the width W, and the distance P′ is almostthe same as the distance P.

In this example, the recessed streak 22 a is formed at an angle of 45°with respect to the longitudinal direction of the infusion container 10with multiple chambers. This angle is not particularly limited but ispreferably from 30 to 60°. In FIG. 2, the arrow direction is thelongitudinal direction of the infusion container 10 with multiplechambers.

In this example, the strong melt-bonding part 15 a is almost uniformlydispersed and distributed in the weak seal part 15 but as long as thetotal occupied area of the strong melt-bonding part 15 a is less than25% of the weak seal part 15, the distribution state thereof may bedifferent in the cross direction of the weak seal part 15, namely, inthe left to right direction in FIG. 1. For example, although not shown,it may be also possible that the strong melt-bonding part 15 a isdensely distributed in the vicinity of the center part in the crossdirection and coarsely distributed in the vicinity of both edge parts inthe cross direction or conversely, the strong melt-bonding part 15 a iscoarsely distributed in the vicinity of the center part in the crossdirection and densely distributed in the vicinity of both edge parts inthe cross direction.

By forming the strong melt-bonding part 15 a to have a differentdistribution state in the cross direction of the weak seal part 15, theweak seal part 15 can be variously adjusted, for example, to provide thedesired state at the peeling and opening or even when the infusioncontainer 10 with multiple chambers falls by mistake and a force isapplied to the edge part in the cross direction of the weak seal part15, not to cause opening of the portion. In order to differentiate thedistributed state of the strong melt-bonding part 15 as such, this maybe attained by using a heat seal bar where a seal edge complying withsuch distribution is formed on the seal surface.

[Second Embodiment]

FIG. 7 shows the weak seal part 15 in an infusion container 10 withmultiple chambers of the second embodiment.

The weak seal part 15 of this example is also formed by sandwichingsuperposed two thermoplastic resin films from both surface side by twoheat seal bars each having a specific seal edge formed on the sealsurface, and has two melt-bonding parts different in the melt-bondingstrength, namely, a strong melt-bonding part 15 a and a weakmelt-bonding part 15 c.

Among these, the strong melt-bonding part 15 a having a highmelt-bonding strength is formed to have a nearly square shape and alinear shape. The linear strong melt-bonding parts 15 a are disposed inparallel with each other at equal intervals and between these, nearlysquare strong melt-bonding parts 15 a are dispersed and distributed. Theportions in the weak seal part 15 except for the strong melt-bondingpart 15 a all are the weak melt-bonding part 15 c having a lowmelt-bonding strength.

Also in this example, the strong melt-bonding part 15 a having a highpeel strength out of those two kinds of melt-bonding parts is formedsuch that the total occupied area thereof is less than 25% of the entirearea of the weak seal part 15, thereby appropriately controlling theopening strength of the weak seal part 15.

Furthermore, also in this example, respective strong melt-bonding parts15 a are dispersed and distributed in the weak seal part 15 such thatthe average space A and average distance B between adjacent strongmelt-bonding parts 15 a satisfy the relationship of formula (1). Theaverage distance B is preferably 1 mm or more, more preferably 1.5 mm ormore, still more preferably 2 mm or more. With this average distance,the opening strength of the weak seal part 15 can be unfailingly andvery easily controlled.

In this case, the space A₁ and distance B₁ between adjacent nearlysquare parts are determined as shown in FIG. 8 similarly to the firstembodiment. On the other hand, the distance B₂ between a linear strongmelt-bonding part 15 a and a strong melt-bonding part 15 a adjacentthereto having a planar shape such as nearly square shape is, when aperpendicular line is drawn from the centroid of the planar strongmelt-bonding part 15 a to the linear strong melt-bonding part 15 a, alength between the above-described centroid and the center point in thecross direction of the linear strong melt-bonding part 15 a on theperpendicular line. The space A₂ is a distance between the distal end ofone strong melt-bonding part 15 a and the distal end of another strongmelt-bonding part 15 a on the perpendicular line. The average space Aand the average distance B are similarly determined by averaging thesespaces or distances.

When the strong melt-bonding part 15 a is formed to have a linear shapeand a planar shape as such, the plane preferably has an area of 1 mm² orless and the line preferably has width of 1 mm or less. In the case ofthe planar shape, the shape is not limited to the nearly square form butmay be other polygonal form or circular form.

This weak seal part 15 of the infusion container 10 with multiplechambers can be formed by sandwiching superposed two thermoplastic filmsfrom both surface sides using two heat seal bars 23 and 24 where a sealedge 23 a or 24 a as shown in FIG. 9 is formed on the seal surface.

Out of two heat seal bars 23 and 24 shown in FIG. 9, one heat seal bar23 has a seal edge 23 a as used in the first embodiment, which isobtained by forming a plurality of projected streaks to run in parallelwith each other on the seal surface. Another heat seal bar 24 has a sealedge 24 a which comprises a large number of nearly square projectedplanes distributed like a lattice at equal intervals. These heat sealbars sandwich the thermoplastic resin film such that the projectedstreak seal edge 23 a of one heat seal bar 23 and the projected plane 24a of another heat seal bar 24 are dislocated from each other.

As a result, the portion contacted and pressed by the seal edge 23 a or24 a from either one surface side of the thermoplastic resin filmbecomes a strong melt-bonding part 15 a which is strongly melt-bonded,and the portion not contacted from both surface sides by either the sealedge 23 a or 24 a of the heat seal bars 23 and 24 is heated indirectlyby heat conduction or the like and becomes a weak melt-bonding part 15 cwhich is weakly melt-bonded.

Here, by using heat seal bars 23 and 24 where the width, distance anddepending on the case, edge angle of each of the seal edges 23 a and 24a are appropriately adjusted in advance such that the total of areas ofthe portions contacted and pressed from either one surface side of thethermoplastic resin film by seal edges 23 a or 24 a is less than 25% ofthe entire weak seal part 15, a weak seal part 15 having a fixed openingstrength can be easily formed. In the case of using such heat seal bars23 and 24, the width of the seal edge 23 a which is a plurality ofprojected streaks formed almost in parallel is preferably 1 mm or lessand the distance is preferably 1 mm or more. The area of the seal edge24 a which is a projected plane is preferably 1 mm² or less.

As seen in FIG. 10 showing the cross-sectional view cut along theIII-III′ line of FIG. 8, the thus-formed weak seal part 15 a of theinfusion container 10 with multiple chambers of this example is in thestate that a recessed part is formed resulting from the seal edge 23 aor 24 a of the heat seal bar 23 or 24 coming into contact with thethermoplastic resin film. In the case of this example, the recessed partis formed on both surfaces of the weak seal part 15, more specifically,recessed streaks 22 a are formed on one surface and nearly squarerecessed planes 22 b are formed on another surface. The portion wherethe recessed streak 22 a is formed and the portion where the recessedplane 22 b is formed both are the strong melt-bonding part 15 a.

The thus-formed recessed streak 22 a corresponds to the width ordistance of the seal edge of the heat seal bar used. The width is thesame as or slightly greater than the width of the seal edge and thedistance is almost the same as the distance of the seal edges. In thethus-formed recessed streak 22 a, the width is 1 mm or less and thedistance from each other is 1 mm or more. The area of the recessed plane22 b is almost the same as the area of the seal edge composed of aprojected plane and is preferably 1 mm² or less.

Such a weak seal part 15 consisting of a strong melt-bonding part 15 aand a weak melt-bonding part 15 c can also be formed by using afilm-made mold having higher heat resistance than the thermoplastic filmused and having formed thereon holes corresponding to strongmelt-bonding parts 15 to be formed. When the thermoplastic resin film isheated through this mold, the portions corresponding to the holes becomethe strong melt-bonding part 15 a which is strongly melt-bonded, andother portions become the weak melt-bonding part 15 c.

[Third Embodiment]

FIG. 11 shows the weak seal part 15 in an infusion container 10 withmultiple chambers of the third embodiment.

The weak seal part 15 of this example is also formed by sandwichingsuperposed two thermoplastic resin films from both surface sides by twoheat seal bars and has a strong melt-bonding part 15 a and a weakmelt-bonding part 15 c.

Among these, the strong melt-bonding part 15 a having a highmelt-bonding strength is formed to have a nearly square shape. Theportions in the weak seal part 15 except for the strong melt-bondingpart 15 a all are the weak melt-bonding part 15 c having a lowmelt-bonding strength.

Also in this example, the strong melt-bonding part 15 a is formed suchthat the total occupied area thereof is less than 25% of the entire areaof the weak seal part 15, whereby the opening strength of the weak sealpart 15 is appropriately controlled.

This weak seal part 15 of the infusion container 10 with multiplechambers can be formed by sandwiching superposed two thermoplastic filmsfrom both surface sides using a heat seal bar having a seal edge 24 acomprising a large number of nearly square projected planes distributedlike a lattice at equal intervals, shown by the numeral 24 in FIG. 9,and a heat seal bar having a planar seal surface (not shown) where aseal edge is not formed. The portion sandwiched and pressed by the sealedge 24 a composed of a projected plane and the planar seal surfacebecomes the strong melt-bonding part 15 a which is strongly melt-bonded,and the portion contacted from one surface side only by the planar sealsurface of the heat seal bar becomes the weak melt-bonding part 15 c.

Also in this case, when the heat seal bar is selected and used such thatthe total occupied area of the strong melt-bonding part 15 a formed asabove is less than 25% of the entire weak seal part 15, a stable weakseal part 15 having a fixed peel strength can be easily formed. In usingsuch a heat seal bar, the area of the seal edge 24 a composed of aprojected plane is also preferably 1 mm² or less.

As seen in FIG. 12 showing the cross-sectional view cut along the IV-IV′line of FIG. 11, the thus-formed weak seal part 15 of the infusioncontainer 10 with multiple chambers of this example is in the state thata recessed part, specifically, a recessed plane 22 b is formed only onone surface resulting from the seal edge of the heat seal bar cominginto contact with the thermoplastic resin film. In the case of thisexample, the recessed parts all are the strong melt-bonding part 15 a.

When the recessed plane 22 b is formed using a heat seal bar 24 having aseal edge 24 a composed of a projected plane having an area of 1 mm² orless, the area thereof is also almost 1 mm² or less.

In forming the weak seal part 15 of this example, the strongmelt-bonding part 15 a and the weak melt-bonding part 15 c can also beformed by the following method. The entire of the portion in which theweak seal part 15 is formed is sealed by a heat seal bar having a planarseal surface (not shown) where a seal edge is not formed, and thisportion is further heated by a heat seal bar having a seal edge 24 acomprising a large number of nearly square projected planes distributedlike a lattice at equal intervals, shown by the numeral 24.

In these infusion containers 10 each having multiple chambers of firstto third embodiments, the weak seal part 15 is particularly formed tohave a plurality of melt-bonding parts different in the melt-bondingstrength and the strong melt-bonding part 15 a having a largestmelt-bonding strength among these melt-bonding parts is dispersed anddistributed in the weak seal part 15 and is controlled such that thetotal occupied area thereof is less than 25% of the area of the weakseal part 15, whereby the opening strength of the weak seal part 15 isappropriately controlled and the weak seal part thus formed can maintainthe liquid-tight separation between the medicament chambers 11 and 12 atan ordinary time but when a force is externally applied to themedicament chamber 11 or 12, can be easily opened. Furthermore, even ifthe thermoplastic resin film used is a single layer film havingcrystallinity and is sealed at a temperature near the melting pointthereof and also the heat sealing temperature is slightly changed, thedispersion in the opening strength of the weak seal part 15 can besuppressed to the minimum and an infusion container 10 with multiplechambers having a fixed performance can be stably produced.

EXAMPLES

The present invention is described in greater detail below by referringto Examples.

Example 1

A 300 μm-thick film comprising a linear low-density polyethylene (MFR: 2g/10 min (190° C.), density: 0.925 g/cm³, JIS K6760) was prepared by awater-cooling inflation method.

Two sheets of this film were superposed and sandwiched from both surfacesides by two heat seal bars to form a peelable and openable weak sealpart 15 and an unpeelable strong seal part 16, thereby producing aninfusion container 10 with multiple chambers of the same type as shownin FIG. 1. At this time, the weak seal part 15 was formed to a length of10 mm at the center part in the longitudinal direction of the infusioncontainer 10 with multiple chambers. In the two heat seal bars usedhere, a large number of projected streak seal edges were formed almostin parallel as shown in FIG. 4 and the seal edge had a width W of 0.2mm, a distance P of 2 mm and an edge angle α of 90°. The total occupiedarea of the strong melt-bonding part 15 a in the weak seal part 15 was4% in all cases.

Also, the sealing was performed under a sealing pressure of 0.39 MPa fora sealing time of 4 seconds at three kinds of heat sealing temperatures,namely, 118° C., 119° C. and 120° C. That is, three kinds of infusioncontainers 10 each having multiple chambers were produced, which weredifferent only in the heat sealing temperature.

Thereafter, 1,000 ml of colored water in place of a medicament wasfilled in each of two medicament chambers 11 and 12 of respectiveinfusion containers 10 with multiple chambers produced above and onemedicament chamber 11 or 12 was pressed at a rate of 500 mm/minute by aplate of 100 mm×100 mm using a compression tester (RTC1250A,manufactured by Orientec). The load when the weak seal part 15 wasopened was measured and used as the opening strength of the weak sealpart 15.

As a result, the opening strength of the weak seal part 15 was 253N inthe case of the infusion container 10 with multiple chambers produced ata heat sealing temperature of 118° C., 760N in the case of 119° C. and1,267N in the case of 120° C. The elevation rate of the opening strengthat 300 to 1,000N (change in the opening strength per 1° C.) was as smallas 507 N/° C. and this reveals that the opening strength is not greatlychanged even if the heat sealing temperature is slightly fluctuated.

Furthermore, 1,000 ml of colored water was filled in each of twomedicament chambers 11 and 12 of respective infusion containers 10 withmultiple chambers, each container was placed on a flat table, and bothmedicament chambers 11 and 12 were alternately pressed by hand 5 timesin total. As a result, the weak seal part 15 was entirely peeled apart(when the weak seal part was entirely peeled apart within 5 times, theopenability is shown by ◯ in Table 1).

In the weak seal part 15 of each infusion container 10 with multiplechambers, the width W′ and distance P′ (see FIG. 6) of the recessedstreak were 2 mm and 0.4 mm, respectively, and the average space A andaverage distance B in formula (1) were 1.6 mm and 2 mm, respectively.These were measured by using a photograph of the weak seal part 15 takenat a magnification of 20 times.

These results and others are shown together in Tables 1 and 2.

Example 2

Three kinds of infusion containers 10 each having multiple chambers wereproduced in the same manner as in Example 1 except that the width W,distance P and edge angle α of the seal edge of two heat seal bars usedwere 0.2 mm, 4 mm and 90°, respectively, and temperatures of 120° C.,121° C. and 122° C. were used as the heat sealing temperature. In theweak seal part 15, the total occupied area of the strong melt-bondingpart 15 a was 0.6% in all cases.

These were evaluated in the same manner as in Example 1 and the resultsobtained are shown in Tables 1 and 2.

As seen from Table 2, the elevation rate of the opening strength wassmall at the opening strength of 300 to 1,000N and this reveals that theopening strength is not greatly changed even if the heat sealingtemperature is slightly fluctuated. The openability was good.

Comparative Example 1

Two kinds of infusion containers 10 each having multiple chambers wereproduced in the same manner as in Example 1 except that the width W,distance P and edge angle α of the seal edge of two heat seal bars usedwere 0.4 mm, 1 mm and 90°, respectively, and temperatures of 117° C. and118° C. were used as the heat sealing temperature. In the weak seal part15, the total occupied area of the strong melt-bonding part 15 a was 25%in either case.

These were evaluated in the same manner as in Example 1 and the resultsobtained are shown in Tables 1 and 2.

As seen from Table 2, the elevation rate of the opening strength waslarge at the opening strength of 300 to 1,000N and this reveals that theopening strength is greatly changed even if the heat sealing temperatureis slightly fluctuated. The openability was bad (shown by X in Table 2)and a part of the weak seal part 15 was not peeled apart.

Comparative Example 2

Two kinds of infusion containers 10 each having multiple chambers wereproduced in the same manner as in Example 1 except that the width W,distance P and edge angle α of the seal edge of two heat seal bars usedwere 0.2 mm, 2 mm and 150°, respectively, and temperatures of 117° C.and 118° C. were used as the heat sealing temperature. In the weak sealpart 15, the total occupied area of the strong melt-bonding part 15 awas 30% in either case.

These were evaluated in the same manner as in Example 1 and the resultsobtained are shown in Tables 1 and 2.

As seen from Table 2, the elevation rate of the opening strength waslarge at the opening strength of 300 to 1,000N and this reveals that theopening strength is greatly changed even if the heat sealing temperatureis slightly fluctuated. The openability was bad and a part of the weakseal part 15 was not peeled apart.

Example 3

Three kinds of infusion containers 10 each having multiple chambers wereproduced in the same manner as in Example 1 except that a heat seal barhaving a seal edge comprising projected streaks as shown in FIG. 9, anda heat seal bar having a seal edge comprising projected planes (squareprojected planes were uniformly present like a lattice) were used incombination as the two heat seal bars, the seal edge in either form hada width W of 0.2 mm, a distance P of 4 mm and an edge angle α of 90°,and temperatures of 118° C., 119° C. and 120° C. were used as the heatsealing temperature. In the weak seal part 15, the total occupied areaof the strong melt-bonding part 15 a was 8% in all cases.

These were evaluated in the same manner as in Example 1 and the resultsobtained are shown in Tables 1 and 2.

As seen from Table 2, the elevation rate of the opening strength wassmall at the opening strength of 300 to 1,000N and this reveals that theopening strength is not greatly changed even if the heat sealingtemperature is slightly fluctuated. The openability was good.

In Table 1, the average distance A₁ and the average distance B₁ weremeasured, as shown in FIG. 8, between strong melt-bonding parts 15 awhich are a recessed plane, and the average distance A₂ and the averagedistance B₂ were measured between a strong melt-bonding part 15 a whichis a recessed plane, and a strong melt-bonding part 15 a which is arecessed streak.

Example 4

Three kinds of infusion containers 10 each having multiple chambers wereproduced in the same manner as in Example 1 except that a heat seal barhaving a seal edge of the type shown by 24 in FIG. 9, which comprises(square) projected planes, and a heat seal bar with a planar sealsurface not having a seal edge were used in combination as the two heatseal bars, the seal edge comprising projected planes had a width W of0.2 mm, a distance P of 2 mm and an edge angle of 60°, and temperaturesof 120° C., 121° C. and 122° C. were used as the heat sealingtemperature. In the weak seal part 15, the total occupied area of thestrong melt-bonding part 15 a was 1% in all cases.

These were evaluated in the same manner as in Example 1 and the resultsobtained are shown in Tables 1 and 2.

As seen from Table 2, the elevation rate of the opening strength wassmall at the opening strength of 300 to 1,000N and this reveals that theopening strength is not greatly changed even if the heat sealingtemperature is slightly fluctuated. The openability was good.

Comparative Example 3

Two kinds of infusion containers 10 each having multiple chambers wereproduced in the same manner as in Example 1 except that two heat sealbars each having a planar seal surface where a seal edge is not formedwere used in combination and two kinds of temperatures, namely, 117° C.and 118° C., were used as the heat sealing temperature. In the weak sealpart 15, the total occupied area of the strong melt-bonding part 15 awas 100% in either case.

As seen from Table 2, the elevation rate of the opening strength waslarge at the opening strength of 300 to 1,000N and this reveals that theopening strength is greatly changed even if the heat sealing temperatureis slightly fluctuated. The openability was bad and a part of the weakseal part 15 was not peeled apart. TABLE 1 Weak Seal Part of InfusionContainer with Multiple Chambers Heat Seal Bar Occupied Area of Strong P(mm) W (mm) α (mm) P′ (mm) W′ (mm) Melt-Bonding Part (%) B (mm) A (mm)Example 1 2 0.2 90 2 0.4 4 2 1.6 Example 2 4 0.2 90 4 0.3 0.6 4 3.7Example 3 4 0.2 90 4 0.3 8 4(B₁) 3.7(A₁) 2(B₂) 1.7(A₂) Example 4 2 0.260 2 0.2 1 2 1.8 Comparative 1 0.4 90 1 0.5 25 1 0.5 Example 1Comparative 2 0.2 150  2 1.1 30 2 0.9 Example 2 Comparative — — — — —100 — — Example 3

TABLE 2 Elevation Opening Strength (N) Rate of at Each SealingTemperature Opening 117 118 119 120 121 122 Strength Liquid (° C.) (°C.) (° C.) (° C.) (° C.) (° C.) (N/° C.) Leakage Openability Example 1 253 760 1267  507 ◯ ◯ Example 2  501 771 1041  270 ◯ ◯ Example 3  321850 1379  529 ◯ ◯ Example 4  366 633  900  267 ◯ ◯ Comparative 630 18601230 ◯ X Example 1 Comparative 540 1640 1100 ◯ X Example 2 Comparative720 1900 1180 ◯ X Example 3

After a liquid was filled in the medicament chambers 11 and 12, leakageof the liquid into the weak seal part 15 was not observed with an eye inall of the infusion containers 10 with multiple chambers, obtained inExamples 1 to 4 and Comparative Examples 1 to 3.

INDUSTRIAL APPLICABILITY

As described in the foregoing pages, in the infusion container withmultiple chambers of the present invention, the total occupied area ofthe strong melt-bonding part in the weak seal part is less than 25%, sothat the peel strength of the boundary portion between one and anotherof multiple medicament chambers is stabilized irrespective of theconstruction material and structure of the film. Furthermore, accordingto the production method of the present invention, such an infusioncontainer with multiple chambers can be easily produced with goodproductivity.

1. An infusion container with multiple chambers, which is formed from athermoplastic resin film and has a plurality of medicament chambers forhousing medicaments, wherein the medicaments chambers are liquid-tightlysealed by a peelable weak seal part, said weak seal part is formed tohave a plurality of melt-bonding parts different in the melt-bondingstrength, the strong melt-bonding part having a largest melt-bondingstrength among said melt-bonding parts is dispersed and distributed insaid weak seal part, and the total occupied area of the strongmelt-bonding part is less than 25% of the area of said weak seal part.2. The infusion container with multiple chambers as claimed in claim 1,wherein respective strong melt-bonding parts are distributed such thatthe average space A and average distance B between adjacent strongmelt-bonding parts satisfy the following formula (1):B<2A   (1)
 3. The infusion container with multiple chambers as claimedin claim 2, wherein said average distance B between strong melt-bondingparts is 1.0 mm or more.
 4. The infusion container with multiplechambers as claimed in any one of claims 1 to 3, wherein each strongmelt-bonding part is a plane having an area of 1 mm² or less and/or aline having a width of 1 mm or less.
 5. The infusion container withmultiple chambers as claimed in any one of claims 1 to 4, wherein atleast one surface of the weak seal part has a recessed part and at leasta part of said recessed parts are the strong melt-bonding part.
 6. Theinfusion container with multiple chambers as claimed in claim 5, whereinsaid recessed part comprises a plurality of recessed streaks formedalmost in parallel and each having a width of 1 mm or less and/or aplurality of recessed planes each having an area of 1 mm² or less. 7.The infusion container with multiple chambers as claimed in claim 5 or6, wherein one surface of the weak seal part has the recessed part andanother surface is planarly formed.
 8. The infusion container withmultiple chambers as claimed in claim 5 or 6, wherein both surfaces ofthe weak seal part have the recessed part.
 9. The infusion containerwith multiple chambers as claimed in any one of claims 1 to 8, whereinthe dispersed state of respective strong melt-bonding parts is differentin the cross direction of the weak seal part.
 10. A method for producingan infusion container with multiple chambers, which has a plurality ofmedicament chambers for housing medicaments and in which saidmedicaments chambers are liquid-tightly sealed from each other by apeelable weak seal part, said method comprising: a weak seal step ofsandwiching superposed two thermoplastic resin films from both surfacesides using two heat seal bars to form a weak seal part having aplurality of melt-bonding parts different in the melt-bonding strength,wherein said weak seal step is performed such that the total occupiedarea of the strong melt-bonding part having a largest melt-bondingstrength among said melt-bonding parts and being dispersed anddistributed in said weak seal part is less than 25% of the area of saidweak seal part.
 11. The method for producing an infusion container withmultiple chambers as claimed in claim 10, wherein a seal edge is formedon the seal surface of at least one of said heat seal bars.
 12. Themethod for producing an infusion container with multiple chambers asclaimed in claim 11, wherein said seal edge comprises a plurality ofprojected streaks formed almost in parallel and each having a width of 1mm or less and/or a plurality of projected planes each having an area of1 mm² or less.
 13. The method for producing an infusion container withmultiple chambers as claimed in claim 11 or 12, wherein a seal edge isformed on the seal surface of one heat seal bar and the seal surface ofanother heat seal bar is formed planarly.
 14. The method for producingan infusion container with multiple chambers as claimed in claim 11 or12, wherein a seal edge is formed on the seal surface of both heat sealbars.
 15. The method for producing an infusion container with multiplechambers as claimed in any one of claims 11 to 14, wherein the averagedistance between respective seal edges is 1.0 mm or more.
 16. The methodfor producing an infusion container with multiple chambers as claimed inany one of claims 11 to 15, wherein the edge angle of each seal edge is120° or less.
 17. The method for producing an infusion container withmultiple chambers as claimed in any one of claims 10 to 16, wherein saidmethod comprises a strong seal step of sandwiching at least a part ofthe peripheral edge of said infusion container with multiple chambersfrom both surface sides by heat seal bars to liquid-tightly close saidperipheral edge part and said strong seal step and said weak seal stepare simultaneously performed.
 18. The method for producing an infusioncontainer with multiple chambers as claimed in any one of claims 10 to17, wherein the weak seal step is performed such that the elevation rateof the opening strength in the weak seal part with respect to the heatseal temperature is 1,000 N/° C. or less.